The present invention relates generally to systems for fabricating high-voltage insulators, and more specifically to a method of improving the flashover strength of high-voltage insulators in vacuum.
High-voltage insulators in vacuum are prone to breakdown across surfaces (flashover) at voltages which are much lower than are required to cause breakdown through the material itself. The task of improving the flashover strength of high-voltage insulators is alleviated, to some extent, by the systems described in the following U.S. Patents, the disclosures of which are specifically incorporated herein by reference:
U.S. Pat. No. 3,972,059 issued to DiStefano;
U.S. Pat. No. 4,065,780 issued to Ballantyne;
U.S. Pat. No. 4,104,693 issued to Toda et al;
U.S. Pat. No. 4,161,814 issued to Ballantyne;
U.S. Pat. No. 4,652,753 issued to Shiokawa;
U.S. Pat. No. 4,256,780 issued to Gaerttner et al; and
U.S. Pat. No. 4,372,646 issued to Strahan et al.
The above-cited references, especially that of Gaerttner et al, recognize that treatments which deposit a small amount of metal on these surfaces, whether fired in place (as on a ceramic insulator) or vacuum deposited (as on a polymeric insulator) improve flashover performance: that is, the voltage at which flashover occurs increases. Techniques for depositing small amounts of metal on ceramic insulators are high temperature processes and are therefore unsuitable for treatment of polymeric materials. Vapor deposition of metal onto polymeric insulator materials generally results in a surface coating susceptible to mechanical damage and to damage from tracking if flashover occurs.
The improvement in flashover performance represents an ongoing need wherever it is necessary to operate with high voltage in a vacuum environment, and may be applied to spacecraft systems, particle-beam accelerators, and other types of research equipment. The present invention is intended to provide a technical advance to help satisfy that need.